Lighting devices have long had the ability to be dimmed. Dimming is essentially a one-dimensional problem. Only a single control, typically implemented as a dial or slider, is necessary to control the intensity of light. The introduction of color-capable lights such as light emitting diodes (LEDs) presents a more complex set of issues to solve when developing controls for them.
Typically these lights are made up of red, green and blue (RGB) emitters that can combine to create any shade of color. Light emitting diodes (LEDs) lend themselves as almost perfect emitters. They are low power, long lasting and easy to control. With more usage, their cost has been lowered dramatically. There are many companies producing light fixtures utilizing RGB LEDs to create colored light. The vast majority of these light fixtures use a communication interface called DMX-512 to receive command information from a central light controller. DMX-512 has its origins in the stage lighting industry and has its own installation and safety requirements. DMX-512 is a standard protocol by means of which theatre lighting control desks can communicate with lighting equipment. It was designed to allow equipment from different companies to be used together easily. Originally developed to control lighting dimmers, it is now used to control color scrollers, moving lights, smoke machines and almost any equipment that can be controlled digitally.
Originally designed to control single color lights it associated a single light to a single slider control on a control panel. Three or more sliders on the control panel typically control color capable lights (i.e. LEDs) today. In the simplest form of control there is one slider for each of the red, green and blue channels. It is up to the user to understand how much of each primary color to set to get a particular color. More complex controllers use built in software programs that understand the characteristics of each light fixture attached to the controller to select colors. DMX-512 light controllers are typically expensive, ranging from the low hundreds of dollars to tens of thousands of dollars. Selecting a specific color is not intuitive.
LEDs emit a very narrow band of light spectra. As a result colors mixed from red, green and blue LEDs may have a non-natural look to the human eye, especially as the colors selected become less saturated (more white). Light manufacturers are including additional colored and white LEDs to improve color fidelity and rendering index. These fixtures require adding additional color channels when mapped to a DMX-512 interface increasing control complexity and cost. For example, setting a specific shade of pink by directly controlling red, green, blue, yellow and white sliders become a challenge.
To date this problem has been manageable because commercial installations can absorb the cost of expensive DMX-512 controllers, and lighting control personnel are capable of controlling complex lights. However as color-capable lights move into the residential arena, the current industry has few intuitive ways for homeowners to control these sophisticated lights.
Typical methods today include:
                Direct red, green, blue color control;        Preprogrammed colors, usually selected by button or color dial;        Presets which must be programmed using an external computer; or        Computer programs requiring access to a computer.The most sophisticated systems on the market today include:        Philips® LivingColors light with a remote control presenting a color wheel        Renaissance® Lighting PDA touchscreen control        
One color model that is more intuitive than most is the Hue-Saturation-Value (HSV) model or sometimes known as the Hue-Saturation-Intensity (HSI) model. It is a three-dimensional color model. One axis controls the color's hue (or actual color value). The hue is generally the single word that we would use to describe a ‘composite’ color. A second axis controls the color's saturation. Saturation specifies how pure the color is. A fully saturated color has no white component in it. White is the unsaturated value. A pure red is fully saturated. Pink is a less saturated red. The third axis controls the intensity of the light.
The hue, saturation and brightness of a light beam are often specified using a three-dimensional HSV or HSI color tree (color space), as shown in FIG. 1. The tree represents one horizontal slice of the total color spectrum represented by a cylinder. The vertical axis 10 of the tree specifies the intensity (lightness) of the beam, from nothing at the bottom (that is, black 12) through gray 14 to some maximum value 16 at the top corresponding to the brightest possible white. At each level of the tree (which corresponds to a given lightness or brightness), we draw a hue circle 18 whose circumference shows the various pure, fully saturated, monochromatic colors of the rainbow in wavelength order from red to violet. The shown Hue circle 18 represents but one slice of a cylinder going from black 12 at the bottom to the maximum value 16 or brightest value at the top. The points on a radius line from the center of the tree to some point on the circumference represent saturation via different unsaturated colors formed by mixing some amount of white from the center of the tree with some amount of the color at the end point of the line. These color models are implemented in many computer systems for use by graphic artists when modifying images. As shown in FIG. 1, pink is a mixture of red and white, and the hue of the mixture is still red. Mixtures of yellow and white would produce colors that we would still call yellow, but which also might be described as “cream” white, “warm” white, etc.
The problem is to easily control a light's intensity and color. Although mathematically color may be specified a number of ways, a control interface must present an intuitive and simple model for a user. Controlling individual color channels is not intuitive. In addition a control system should be independent of the lighting system it controls. This allows the lighting system to implement color generation with any mechanism. Finally, a control system should be low-cost to implement.
The present invention solves these problems as will be described herein using a two dimensional touchpad or touch screen. In a home this mini touchpad could be a wall mounted device.